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Sign Language Improves Your Mental Rotation Abilities

Look at the picture below: if you stick the unfolded cube in a T on the left, which cube is shaped between options a, b, c and d on the right? To solve this task you will need great mental rotation abilities and people who learn Sign Language solve it faster.

Mental rotation game: which of the images on the right results from sticking the cube on the left? (source: Smart Kit)

Why Is Mental Rotation Ability So Important?

Mental rotation is the ability to rotate images of objects mentally. This ability is important for numerous daily tasks: discovering if an object has changed location, solving a Rubik's cube or puzzles, controlling space in some sports, reading and navigating on a map, jobs like architecture or handicraft, and so on. In general, the ability to rotate metal is related to intelligence.

Mental rotation game

The Research

Although there are several studies, one of the most comprehensive was conducted in 1993 by the Salk Institute and the prestigious Harvard University in the United States, and was published in the Cognition scientific journal, the magazine with the largest impact factor in the world in its field.

The research was conducted on a group of 84 people with the following characteristics:

A group of 40 profoundly Deaf people, of whom 12 learned Sign Language from birth and 12 did not. Of these 12 non-native signers, two groups: those who learned Sign Language between the ages of 2 and 8, and those who learned Sign Language between the ages of 12 and 16.

A group of 34 hearing people, without any experience with Sign Language.

A group of 10 hearing people from Deaf families who learned Sign Language from childhood, so they were bilingual in American Sign Language and English.

The researchers conducted several experiments: one that tested the ability to generate mental images, another to test the ability to retain an image in short-term memory, and a final experiment to examine the ability of mental rotation of images of objects. This last experiment involved recognizing figures mirror's rotated or on their axis on a model.

Examples of mental rotation. On the left, the original model of the figure. Above, the same figure rotated on its axis. Below, the figure rotated on its axis and mirrored. (picture: Emmorey, Kosslyn y Bellugi 1993).

The results showed that Deaf people were faster in all experiments but in retaining images in short-term memory. Deaf people and hearing people from Deaf families (i.e. those who learned Sign Language in their childhood) have a greater ability to produce mental images and detect object mirror inversion. In the mental rotation experiment, Deaf people were faster than hearing people who did not know Sign Language even when there was no rotation of the figure. The time difference was greatest when the represented object was rotated 180 degrees.

Response times in mental rotation tasks for Deaf people (dashed line) and hearing people without Sign Language experience (dashed line). Horizontal: degrees of rotation of the figure. Vertical: reaction time in milliseconds (graph: Emmorey, Kosslyn y Bellugi 1993).

Finally, the age at which Sign Language was learned did not impact on its ability to generate mental images or retain an image, showing that Sign Language can be a benefit at any age. However, native signers were more accurate (had fewer mistakes) than non-native signers in the mental rotation task and, in any case, always faster in this task than people who did not know Sign Language.

Why Does Sign Language Improve the Ability of Mental Rotation?

Sign languages are visual and gestural languages that use space for their presentation. A very obvious example of mental rotation in sign language is when describing the position of objects in space since the person who does the description has a perspective, and the other person must do a mirror mental rotation to his own perspective (see picture below).

Change of perspective between the signer and the recipient person: for the signer, the lamp is on the left from its perspective. For the recipient person, the lamp is on the right from its own perspective. By turning the semicircle 180º to the left we see that the disposition matches. The recipient has to do an effort of mental rotation (picture: Emmorey, Kosslyn y Bellugi 1993).